Don't think we can argue with that really. Only really Hamer that has worked out. Jobello may have been ok in league one if not for injury. Other than that can't think of another success.
The thing that lets Hamer down for me is the bookings. He's going to end up missing 6 games over the course of this season due to bookings.
Like most others, for me it's Gyökeres > O'Hare > Hamer.